The CDR only counts 3 years worth of stats, took me 5 years to default and they hire a company to harass students to defer past that 3 year window anyway so this number is vastly understated.
http://www.institutionalinvestor.com/article/3498719/asset-management-hedge-funds-and-alternatives/hedge-funds-smell-blood-in-the-student-debt-market.html